The high temperature growth behavior of epitaxial LaGaO 3 thin films with and without SrO is determined with real-time X-ray scattering. In this study, we find SrO alters the thin film growth mode of LaGaO 3, both when predeposited on a surface as well as when SrO and LaGaO 3 are codeposited. We also find that depositing a small amount of SrO on a LaGaO 3 surface induces significant structural rearrangement in the film. We describe mechanisms under which these transformations can occur. In conclusion, the strong effect of SrO on the microstructure of La 1–xSr xGaO 3 likely has wider implications for other ionically conducting oxide materials.

@article{osti_1352576,
title = {Effect of SrO Doping on LaGaO3 Synthesis via Magnetron Sputtering},
author = {Highland, Matthew J. and Perret, Edith and Folkman, Chad M. and Fong, Dillon D. and Thompson, Carol and Fuoss, Paul H. and Eastman, Jeffrey A.},
abstractNote = {The high temperature growth behavior of epitaxial LaGaO3 thin films with and without SrO is determined with real-time X-ray scattering. In this study, we find SrO alters the thin film growth mode of LaGaO3, both when predeposited on a surface as well as when SrO and LaGaO3 are codeposited. We also find that depositing a small amount of SrO on a LaGaO3 surface induces significant structural rearrangement in the film. We describe mechanisms under which these transformations can occur. In conclusion, the strong effect of SrO on the microstructure of La1–xSrxGaO3 likely has wider implications for other ionically conducting oxide materials.},
doi = {10.1021/acs.cgd.6b00914},
journal = {Crystal Growth and Design},
number = 12,
volume = 16,
place = {United States},
year = {2016},
month = {10}
}

In-situ synchrotron x-ray scattering has been used to monitor and control the synthesis of LaGaO 3 epitaxial thin films by 90° off-axis RF-magnetron sputtering. We compared films deposited from a single LaGaO 3 source with those prepared by alternating deposition from separate La 2O 3 and Ga 2O 3 sources. The conditions for growth of stoichiometric films were determined by real-time monitoring of secondary phase formation as well as from features in the diffuse scatter from island formation during synthesis. Our results provide atomic-scale insight into the mechanisms taking place during reactive epitaxial growth and demonstrate how in-situ techniques canmore » be utilized to achieve stoichiometric control in ultrathin films.« less

Effects of small amounts of Fe doping for Ga site in LaGaO{sub 3}-based oxide on oxide ion conductivity is investigated in this study. It is found that doping a small amount of Fe is effective for improving the oxide ion conductivity in La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.2}O{sub 3} (LSGM). The highest oxide ion conductivity was exhibited at x = 0.03 in La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.2{minus}x}Fe{sub x}O{sub 3} among the Fe-doped samples. Electron spin resonance (ESR) measurements suggest that Fe is trivalent in LaGaO{sub 3} lattice. The application of the Fe-doped LaGaO{sub 3}-based oxide for the electrolyte of solid oxidemore » fuel cell was further investigated. Power density of the solid oxide fuel cell was increased by using Fe-doped LSGM for electrolyte. This can be explained by the decrease in electrical resistance loss by improving the oxide ion conductivity. A maximum power density close to 700 mW/cm{sup 2} was obtained at 1,073 K on the cell using 0.5 mm thick La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.17}Fe{sub 0.03}O{sub 3} (LSGMF) and O{sub 2} as the electrolyte and the oxidant, respectively. Therefore, close to the theoretical open-circuit potential was exhibited by the LSGMF cell. On the other hand, the power density was slightly smaller than that of the cell using Co-doped LSGM as electrolyte, especially, at temperatures lower than 973 K. This may result from the large activation energy for ion conductivity. However, the power density of the LSGMF cell was higher than that of the LSGM cell. Therefore, LSGM doped with a small amount of Fe is a promising electrolyte similar to Co-doped LSGM for the intermediate solid oxide fuel cell.« less

In this study, the effects of doping with GeO 2 on the synthesis temperature, phase structure and morphology of (K 0.5Na 0.5)NbO 3 (KNN) ceramic powders were studied using XRD and SEM. The results show that KNN powders with good crystallinity and compositional homogeneity can be obtained after calcination at up to 900°C for 2 h. Introducing 0.5 mol.% GeO 2 into the starting mixture improved the synthesis of the KNN powders and allowed the calcination temperature to be decreased to 800°C, which can be ascribed to the formation of the liquid phase during the synthesis.

Journal ArticleYi, Di
; Liu, Jian
; Hsu, Shang-Lin
; ...May 2016 - Proceedings of the National Academy of Sciences of the United States of America

Magnetic anisotropy (MA) is one of the most important material properties for modern spintronic devices. Conventional manipulation of the intrinsic MA, i.e., magnetocrystalline anisotropy (MCA), typically depends upon crystal symmetry. Extrinsic control over the MA is usually achieved by introducing shape anisotropy or exchange bias from another magnetically ordered material. Here we demonstrate a pathway to manipulate MA of 3d transition-metal oxides (TMOs) by digitally inserting nonmagnetic 5d TMOs with pronounced spin-orbit coupling (SOC). High-quality superlattices comprising ferromagnetic La 2/3Sr 1/3MnO 3 (LSMO) and paramagnetic SrIrO 3 (SIO) are synthesized with the precise control of thickness at the atomic scale.more » Magnetic easy-axis reorientation is observed by controlling the dimensionality of SIO, mediated through the emergence of a novel spin-orbit state within the nominally paramagnetic SIO.« less